1. Field of the Invention
The invention relates to an automatic device for shot-blasting hollow parts of large dimensions, the device comprising a sealed enclosure, and displaceable oscillating shot-blasting ramps disposed in the enclosure.
2. Description of the Prior Art
The devices at present permit the shot-blasting of large area parts by means of ramps on which there are mounted blast pipes which, in certain embodiments, oscillate to permit the sweeping of a relatively large surface. Such devices are described, for example, in the U.S. Pat. Nos. 2,881,506 and 2,933,802. In the first patent cited, the part to be shot-blasted passes in front of a ramp carrying blast pipes to which a reciprocating movement is imparted in the vertical plane controlled by a simple jack acting on a rod. This device only permits the treatment of one face of a panel. In the second patent cited, the panel to be treated is placed on an inclined support and the shot-blasting ramp, surrounded by the sealed cabin, is displaced in front of the panel, the blast pipes effecting an oscillation movement in a vertical plane.
Other devices are known, for example from the German Pat. No. 1 577 550, enabling three faces of a part of relatively small dimensions such as I irons or H irons, to be treated, in which the blast pipes are placed in front of two opposite faces and rotate about the axis of the part to treat the other faces.
None of these devices permits treatment of a large part at at least four of its six sides as the case arises, for example, for containers intended for trucks or for railway cars. Generally, this container has the shape of a rectangular parallelepiped closed at the rear by doors and of which the floor, consisting of supporting beams, does not have to be subjected to shot-blasting. The use of the devices known at present permits a gain in time in comparison with the manual process but necessitates a large number of manipulations to treat the whole of the surface.